Air conditioners essentially work by taking warm air from inside our homes and offices and moving it outdoors. Can this affect the temperature outside? According to a recent study at Arizona State University, it turns out that it can.

The study focused on the effects of air conditioning in a crowded urban environment where large numbers of air conditioners run and where there is a lot of heat: Phoenix, Arizona. Their model showed that over a 10-day period of extreme heat, nighttime temperatures were increased by about 2 degrees Fahrenheit because of the waste heat of air conditioners. During the day, even though air conditioner use was even greater, the effect was minimal because of the nature of the urban boundary layer in the air.

Increasing the air temperature by two degrees further increases the AC demand and therefore, the use of electricity. Air conditioning can consume more than 50 percent of total electricity during heat waves and puts a real strain on electrical grids. The new results show that increased air conditioner use actually leads to even more air conditioner use. It is a positive feedback loop.

So what can be done about this problem? The best solution would be to convert waste heat into useful energy instead of dumping it into the environment. One example would be to use it for water heating. With growing populations in places like Phoenix and with increasingly common heat waves, we cannot ignore the fact that air conditioning is a two-way street.

“Earth Wise” is heard on WAMC Northeast Public Radio and is supported by the Cary Institute.

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